Extended length and higher density packages of bulky yarns and methods of making the same

ABSTRACT

A method of winding bulked continuous filament yarn is disclosed, which enables superior yarn package formation, including higher density packages with excellent shape and yarn takeoff characteristics. The method uses unique helix angles and winding profiles in a non-adjacent and adjacent yarn pattern, achieved by a unique winding control strategy that constantly monitors spindle speed, desired wind ratio, traverse cam speed, and surface speed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims benefit of priority from U.S. ProvisionalApplication No. 61/256,744 filed Oct. 30, 2009.

This invention relates to packages of bulked continuous filament (BCF)yarns and other textured or “bulky” yarns having a greater length ofyarn for a given yarn type and package size than similar packages of thesame yarn wound according to methods of the prior art. The packages ofthe winding process disclosed herein have higher density measured interms of net yarn weight per unit of package volume, providing a greaterweight of yarn per yarn package of similar width and diameter, while thekey quality attributes of bulk and interlace are maintained consistentlythroughout the package. The package of the disclosed invention is alsomore easily unwound than yarn packages of the prior art, withsubstantially reduced unwinding tensions observed at higher take-offspeeds. Also disclosed herein are methods of making bulky yarns usingunique helix angles, adjacent and non-adjacent wind ratios, and windingprofiles.

BACKGROUND OF THE TECHNOLOGY

The mills of the North American carpet industry and their yarn suppliershandle over 200 million BCF yarn packages per year, consisting of yarnwound around heavy paper, plastic or composite rolls, called “tubecores.” Each of these BCF packages normally contain from about 8 to 20pounds of yarn, depending on the bulk of the yarn, where bulk is ameasure of the space taken up by a given weight of yarn. The bulkier theyarn, the less weight the package generally contains. The carpetindustry often uses tube cores, sometime multiple times, depending onthe yarn type and the processes involved. However, the expense of coresis still a substantial cost item. Furthermore, it is important tounderstand that cost is incurred each time a package is handled, both interms of manpower and from risk of damage to both the yarn and the tubecore.

The physical dimensions of the BCF yarn package are not easily changed.The size and makeup of the standard BCF package is set by severalfactors, including the limitations of existing spinning, winding, andunwinding processes and equipment. For example, tube core diameter mustbe large enough to permit smooth unwinding, while it must also be strongenough to permit winding at high speed. The overall diameter of the BCFyarn package is also restricted, in one case by the standard twisterbucket diameter, into which the package must fit. The stroke, or widthof the yarn on the tube core is also set in accordance with existingequipment size and process limitations, including unwinding efficiency.

Several methods of increasing yarn package density have been employed.These include: tighter winding around the tube core and tighter yarnpacking with overlapping loops. These methods, however, have theirunique drawbacks, which include difficulty removing the yarn; loss inbulk property; decrease in package stability; and yarn falling off thecore ends. To avoid the above problems, precision winding and randomwinding methods are used.

Precision Winding is typically used for textile yarns, which are finedenier and flat, meaning they are not bulk textured and so containalmost no “bulk” property. These yarns are typically textured insecondary steps, and the smoothness and uniformity of unwinding is mostimportant to subsequent process productivity. Wound packages of textileyarn are also typically finer denier. Owing to these factors, textileyarn packages typically contain a very much greater length of yarn thanBCF packages and both wind and unwind at higher speeds than is presentlytypical for BCF. A precision winding control method and winding profiledesigned to avoid ribbon formation is provided in U.S. Pat. No.5,056,724 to Prodi and Albonetti, where operating limits areestablished, for example at the ribbon formation winding ratios, andthen avoided. Another profile described in U.S. Pat. No. 6,311,920 toJennings et al is designed to avoid package irregularities by windingadjacent to integral and sub-integral winding ratios and imposing aconsistent offset from each winding ratio throughout the package.

For BCF yarn, it is customary to use a random wind profile in which aconstant helix angle/wind ratio is maintained through adjusting spindlespeed and traverse guide speed. The result of this approach is a randomyarn lay pattern on the BCF package with varied spacing between the yarnthreads throughout the package. This tends to provide a stable packagewith few winding problems, and it avoids the “ribbon” problem describedabove. A somewhat more advanced example of this approach maintains aconstant crossing angle as yarn layers overlap on the package, such asis disclosed by Haak in U.S. Pat. No. 5,740,981, applied to both spindledriven and friction drive winding systems. Randomly wound packages varygreatly in packing density, depending especially on yarn bulk, whereyarns of higher bulk make lighter weight packages.

BRIEF SUMMARY OF THE INVENTION

In recent years, the weight of yarn in a given set of package dimensionshas been gradually reduced as BCF yarns have increased in bulk. For anygiven denier, this translates to shorter yarn lengths per package, withmore tube cores and more package handling per unit of yarn and per yardof fabric. Thus, it can be understood that larger yarn packages might bedesired to reduce cost per unit quantity of yarn if such packages couldbe used effectively.

Therefore, it is desirable to invent a winding method that couldsubstantially increase the package density (yarn weight contained in apackage of a specific size) of bulky yarns compared to randomly woundyarn packages, or precision wound packages of the prior technology. Atthe same time, it is also desirable to maintain or improve the yarn bulklevel, bulk consistency, winding tension, package form stability, andpackage unwinding tension, compared to the prior winding methods.

The invention disclosed herein provides a yarn winding method to makeBCF packages with an increase in packing density from about 2% to about20%, including from about 7% to about 17%, and about 7% to about 11%(yarn weight contained in a package of a specific size) compared torandomly wound yarn packages, or precision wound packages of the priormethods. The BCF packages of the instant disclosure display higher yarnbulk level than the control yarn of the prior methods, with the same orsuperior bulk consistency and package form stability. Spinning windingtension is shown to be lower than the prior winding methods. Packageunwinding tension is lower, compared to the prior methods, especiallywhen unwinding the package at higher speed (e.g. as in packageback-winding). Novel winder spindle and traverse guide controlalgorithms, that enable one skilled in the art to accomplish thedisclosed profile with sufficient precision to be effective are alsodisclosed. Also provided are novel BCF packages made by the variousaspects of the disclosed method.

In one aspect of the disclosed method, the bulky yarn is wound on a tubecore using precision non-adjacent wind ratios until a package diameterbetween about 130 mm to about 180 mm, including from about 150 mm toabout 180 mm, and from about 160 mm to about 180 mm, is achieved. Atthis point, adjacent integral and non-integral precision wind ratios canbe used for the remainder of the yarn winding. Typical bulky yarn woundon a tube core has a final diameter of from about 250 mm to about 280mm, including 275 mm. The final diameter includes a standard tube corediameter of 79 mm. A person of skill in the art would know that tubecore diameters vary and how to modify the winding profile as such.

In another aspect of the disclosed method, the bulky yarn is wound on atube core using non-adjacent random winding until a package diameterbetween about 130 mm to about 180 mm, including from about 150 mm toabout 180 mm, and from about 160 mm to about 180 mm, is achieved. Atthis point, adjacent integral and non-integral precision wind ratios canbe used for the remainder of the yarn winding.

In a further aspect of the disclosed method, the bulky yarn is wound ona tube core using a first non-adjacent set point with a firstnon-adjacent wind ratio and a first helix angle. The wind ratios arestepped increased to additional non-adjacent set points withnon-adjacent wind ratios and helix angles greater than the first helixangle, until a package diameter of from about 130 mm to about 180 mm,including from about 150 mm to about 180 mm, and from about 160 mm toabout 180 mm, is achieved. At this point, the wind ratios are stepincreased to at least one adjacent set point with at least one precisionadjacent wind ratio and at least one helix angle greater than said firsthelix angle.

In yet a further aspect of the disclosed method, the bulky yarn israndomly wound on a tube core using a first non-adjacent set point witha first non-adjacent wind ratio and first helix angle. The wind ratiosare step increased to additional set points until the package diameteris from about 130 mm to about 180 mm, including from about 150 mm toabout 180 mm, and from about 160 mm to about 180 mm. Up to this point,the yarn is laid down on the tube core in a non-adjacent pattern. Thewind ratios are then step increased to a least one adjacent set pointwith at least one precision adjacent wind ratio and at least one helixangle greater than said first helix angle.

In yet another aspect of the disclosed method, the bulky yarn is woundon a tube core using a series of wind ratio set points, more than 10 andless than about 30, including more than 15 and less than 25. Each setpoint starts at a specific wind ratio and helix angle, such that thehelix angle gradually decreases from each initial set point withincreasing package diameter, until a new set point is reached where anew wind ratio and higher helix angle is set, wherefrom the helix angleagain gradually decreases until the next set point. The helix angle atthe starting (or jump) point for each set point of the disclosed methodranges from about 9 degrees at the package core and gradually increasesat the jump points to about 15 degrees at the peak, and then recedes toabout 11 degrees at the jump points at the outer layers of the BCFpackage. Non-adjacent wind ratios can be used for the first 50% to 75%of the set points, while adjacent wind ratios can be used for theremaining 25% to 50% of the set points.

In a further aspect, a bulky yarn wound on a tube core having a packingdensity of from about 0.4 grams per cm³ to about 0.6 grams per cm³,including from about 0.5 grams per cm³ to about 0.55 grams per cm³, isdisclosed. This yarn can be wound using non-adjacent wind ratios untilthe package diameter reaches about 130 mm to about 180 mm, includingfrom about 150 mm to about 180 mm, and from about 160 mm to about 180mm. At this point, adjacent precision wind ratios can be used for theremainder of the yarn winding. This bulky yarn package has animprovement in package density of from about 2% to about 20%, includingfrom about 7% to about 17%, and from about 7% to about 11%, over randomwound packages of the same yarn.

In yet another aspect of the disclosed method, the bulky yarn is woundon a tube core using precision non-adjacent wind ratios until a ratio ofpackage diameter to tube core diameter of from about 1.6:1 to about2.3:1, from about 1.9:1 to about 2.3:1, and from about 2.0:1 to about2.3:1, is achieved. At this point, adjacent integral and non-integralprecision wind ratios can be used for the remainder of the yarn winding.

In yet a further aspect of the disclosed method, the bulky yarn is woundon a tube core, the tube core having an axis, an inner diameter aboutsaid axis, an outer diameter about said axis, an outer circumference anda length; the package having an inner diameter equal to the outerdiameter of the tube core, an outer diameter, a circumference, a widthless than the length of the tube core and having approximately flatsides on planes normal to the axis of the tube core and separated bysaid width, the method comprising:

(a) rotating the tube core about its axis;(b) placing a continuous length of bulked continuous filament yarn incontact with the outer circumference of the tube core at an initiallocation along the length of the tube core;(c) winding said yarn around the outer circumference of the tube coresuch that the yarn is taken up by the tube core and the yarn contactlocation moves around the tube core;(d) causing the yarn contact location to move in a reciprocating motionalong the length of the tube core as the tube core rotates, so that theyarn contact location becomes a moving point on circumference of thepackage as the package rotates and the package outer diameter increases,and so that the contact location traverses the entire width of thepackage from side to side on each traverse stroke, forming a packagesurface at the package outer diameter;(e) selecting a desired contact location traverse speed in relation tothe rotational speed of the rotating package,(f) setting a desired contact location traverse speed control point inrelation to the rotational speed of the rotating package;(g) detecting the actual contact location traverse speed;(h) adjusting the setting for the contact location traverse speedcontrol point so that the actual speed of traverse converges with thedesired speed;(i) selecting a new desired package rotational speed and a new contactlocation traverse speed after a specific time interval;(j) setting the new package rotational speed and yarn contact locationtraverse speed control point at selected time intervals;(k) detecting the new actual contact location traverse speeds;(l) adjusting the settings for the new contact location traverse speedscontrol points so that the actual speeds of traverse converge with thenew desired speeds; and(m) repeating steps (i) through (I) until the package outer diameterreaches a desired value.

In yet even another aspect, a package of bulked continuous filament yarnis disclosed having a ratio of packing density (measured in grams percm³) to final package diameter (measured in cm) greater than 0.018:1.The ratio can also be from 0.018:1 to about 0.022:1, including 0.019:1to about 0.022:1, 0.020:1 to about 0.022:1, and about 0.021:1 to about0.022:1.

In yet even a further aspect, a package of bulked continuous filamentyarn is disclosed having a package density increase between about 7% toabout 17% compared to the package density of a randomly wound packagecontaining said yarn. The package density increase can also be fromabout 7% to about 11%.

In another aspect of the disclosed method, the bulked continuousfilament yarn is wound on a tube core using at least one non-adjacentwind ratio until said package diameter is from about 47% to about 65% ofsaid final package diameter. At this point, the yarn is wound using atleast one precision adjacent wind ratio.

In a further aspect of the disclosed method, the bulked continuousfilament yarn is wound on a tube core using a non-adjacent randomwinding pattern until said package diameter is from about 47% to about65% of said final package diameter. At this point, the yarn is woundusing at least one precision adjacent wind ratio.

In yet another aspect of the disclosed method, the bulked continuousfilament yarn is wound on a tube core using a non-adjacent randomwinding patter until a ratio of package diameter to tube core diameterof from about 1.6:1 to about 2.3:1 is achieved. At this point, the yarnis wound using at least one precision adjacent wind ratio.

In yet a further aspect, a package of bulked continuous filament yarn isdisclosed, comprising a packing density of from about 0.4 grams per cm³to about 0.6 grams per cm³, wherein said package further comprises anon-adjacent winding pattern ending at a package diameter to tube corediameter ratio from about 1.6:1 to about 2.3:1, and a precision adjacentwinding pattern starting at a package diameter to tube core diameterratio from about 1.6:1 to about 2.3:1.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show a step precision winding profile having 22 windratio set points of one aspect of the disclosed method where FIG. 1Arepresents Winding Profile 1 and FIG. 1B represents the wind ratios perstep used to wind Samples 1-9.

FIGS. 2A and 2B show a step precision winding profile having 22 windratio set points of another aspect of the disclosed method where FIG. 2Arepresents Winding Profile 2 and FIG. 2B represents the wind ratios perstep used to wind Sample 10.

FIG. 3 is a winding control strategy according to the disclosed method.

DEFINITIONS

While mostly familiar to those versed in the art, the followingdefinitions of some of the terms used in the instant disclosure areprovided in the interest of clarity.

Adjacent: having little or no space intervening between one winding passand the next on the surface of a yarn package, but where the yarn passesare not actually on top of one another.

Bulk: an inverse measure of yarn density, where higher bulk numbersindicate larger volume occupied by a unit weight of yarn. Bulk isdetermined after the yarn is heat-set.

Crimp: is the waviness or distortion of a textured yarn and isdetermined prior to heat-setting.

Denier: part of product description which is the weight per length ofyarn (grams/9000 meters). The higher the number, the heavier the yarn orfiber.

Non-integral (e.g. half-integer, quarter-integer) wind ratio: a windratio where the number of revolutions of the package per transversestroke is not a whole number (integer). E.g. 3.5 wind ratio creates 7bands as the yarn repeats its traverse stroke and pattern on thepackage.

Integral (Integer) wind ratio: where the number of revolutions of thepackage per traverse stroke is a whole number; at an integral (integer)wind ratio, e.g. 5.0, the wind ratio there would be exactly 5 bands ontop of each other as the yarn repeats its traverse stroke and pattern onthe package.

Helix angle: the apparent angle yarn takes with respect to a planenormal to the axis of the tube core at any given point as it is woundabout a package; this is also the angle of the yarn path with respect toa perfect package side wall (which should form a plane at 90 degrees tothe tube core axis).

Helix angle profile: the relation of helix angle to package diameter.

Jump or step point: a point in time in the winding profile where thepackage rotational speed and the traverse speed move together to a newset point, also making an abrupt change in helix angle.

Package: a length of yarn wound around a tube of heavy paper or othermaterial such that the wound yarn takes on a cylindrical shape somewhatshorter in length than the tube, with clearly defined flat sides ateither end.

Ribbon: synonymous with “band”, ribbons are locations where yarn hasbeen wound up or laid down on a package so that each pass or yarn pathlays immediately on top of the other (at the same winding helix angle).

Traverse: the action of moving a yarn contact point back and forth alongthe length of the tube core as the tube core is being rotated, so thatthe yarn is wound about the tube core to make a package.

Traverse cycle: where the traverse guide or yarn contact point passesfrom an initial reference point on along the axis of the package to oneside of the package, back through the initial reference point to theother side of the package, and then returns to the initial referencepoint.

Traverse guide: a mechanical device to carry a yarn threadline back andforth from one end of the package to the other while it is being woundaround the tube core.

Traverse stroke: the pass of the yarn contact point on the core tube orpackage from one package side to the other; also, the distance betweenthe package sides through which the traverse moves.

Traverse speed: the speed (linear) with which the yarn contact pointtraverses the package; the frequency in cycles per minute with which thetraverse guide completes a stroke and returns.

Tube core: synonymous with tube; a tube made of paper, cardboard, resin,polymer, combinations thereof, or of other structural material suitablefor being rotated at high speed and string enough to resist crushingforce to a suitable degree. A typical tube core has a diameter of about79 mm, however, other diameter available tube cores are available.

Wind ratio: the number of revolutions per minute of the spindle (or tubecore) per complete traverse cycle (complete cycle, to and fro).

DETAILED DESCRIPTION OF THE INVENTION

A method is disclosed of creating a BCF package that is surprisinglyabout 2-20% more dense, including about 7-17% and about 7-11% moredense, than a random wound package of the same yarn type formed at thesame tension, while maintaining package formation within the requireddimensions for BCF Nylon yarn. The method includes unique, electroniccontrols and specific winding settings.

The method is a type of precision winding, for the purpose of improvingpackage formation and unwinding. Precision winding uses a series of windratio steps to control uniform yarn spacing. In stepped precisionwinding, a series of wind ratios are used that form a step patternfollowing a designed helix angle profile (from a graph of helix angle asa function of package diameter). See for example FIGS. 1 and 2.

The highest packing density is adjacent to whole integer and sub-integerribbons as this is where the tightest spacing between threadlinesexists. The desired spacing for adjacent integer wind ratios can bedetermined by the equation 1 provided below:

$\begin{matrix}{D_{y} = {\frac{{WR}_{i} - {WR}_{a}}{{WR}_{i}}*{TR}_{stroke}}} & (1)\end{matrix}$

This equation computes the wind ratio difference between the integerwind ratio (WR_(i)) and the actual wind ratio (WR_(a)) into acenter-to-center threadline spacing (D_(y)). TR_(stroke) is length inunit mm of the distance traveled by the traverse in one direction. Thisequation is useful for determining the wind ratio necessary to achieve aspecified spacing from any given integer ribbon.

The winding settings necessary for increased density with successfulpackage formation of BCF nylon yarn include helix angle range, helixangle profile, and specific wind ratio/yarn spacing determination atspecific diameters throughout the package. BCF yarn can be any bulkedcontinuous filament yarn, for example a bulk continuous filament nylonyarn with a denier range from about 500 to about 2400 and a crimpbetween about 10% to about 40%. Compared to the textile yarn windingprocesses, BCF nylon yarn requires that some special considerations betaken into account when attempting precision winding. This is due to theheavier and bulkier make-up of the yarn coupled with its greater naturallively “springiness” and the finish and additives on the yarn surface,which make it both more susceptible to retraction and more susceptibleto sloughing at the reversals due to low friction. Taken together, thesefactors make BCF package sidewall uniformity very difficult toaccomplish with precision winding. Characteristics inherent to precisionwinding amplify the opportunity for package formation issues due tosloughing at the cam reversals. Closer yarn spacing is typicallyachieved by precision winding, which creates a greater opportunity forpiling of threadlines at the reversals and poor package formation. Also,higher traverse speeds/helix angle precision winding processes tend tohave more sloughing because the yarn is always trailing the traverseguide and the traverse stroke length is essentially shortened.

While maintaining a constant wind ratio over a longer duration of thepackage, the traverse speed is slowing down, and the traverse stroke is,in effect, changing. This slowing down occurs at each wind ratio stepwhere constant wind ratio is maintained. The compounding of this effectthroughout the build of the package makes even sidewall formation verydifficult to accomplish by precision winding processes of the prior art,due to bulging and saddling at the reversals. Due to this phenomenon,several unique modifications had to be made to the winding methoddisclosed herein and the manner of its control, which clearlydistinguish the winding method disclosed herein from the prior art.

FIGS. 1 and 2 represent winding profiles used to wind samples of Nylon6,6 according to various aspects of the disclosed method. A Toray NXA/Bwind-up was used with both winding profiles. This is a 4-end, spindledriven, automatic doff winder that is capable of being converted to a2-end process. This winder is capable of spinning BCF nylon yarn of arange of 650-2600 denier at a surface speed of 1100-3100 meters perminute. The yarn can be spun to a maximum package diameter of 275 mmwith a 263.5 mm traverse stroke using a motor driven cam to traverse theyarn.

FIG. 1A represents Winding Profile 1 and FIG. 1B represents the windratios per step used to wind Samples 1-9 (described below) according toone aspect of the disclosed method. Twenty-two steps are used in WindingProfile 1, where wind ratios that are not adjacent to integral andnon-integral ribbons are used (i.e. non-adjacent wind ratios) for thefirst 13 steps, (i.e. until the package diameter is about 130 mm). Theremaining nine steps are at wind ratios that are adjacent to integraland non-integral ribbons (i.e. adjacent wind ratios).

FIG. 2A represents Winding Profile 2 and FIG. 2B represents the windratios per step used to wind Sample 10 (described below) according toanother aspect of the disclosed process. Twenty-two steps are used inWinding Profile 1, where wind ratios that are not adjacent to integraland non-integral ribbons are used (i.e. non-adjacent wind ratios) forthe first 15 steps (i.e. until the package diameter is about 148 mm).The remaining seven steps are at wind ratios that are adjacent tointegral and non-integral ribbons (i.e. adjacent wind ratios).

Helix Angle Range

BCF nylon yarn requires a wider range of helix angle in order to achievehigher packing density with sufficiently uniform and stable packageformation. In one aspect of the disclosed method, the helix angle rangesfrom about 9 degrees up to about 15 degrees. This allows for goodpackage build at the core with low helix angle and also allows for muchlonger yarn layers having adjacent integral and non-integral ribbonslater in package build.

In another aspect, the method uses the adjacent integer winding ratioslater in package build because speed control is more variable throughquarter integer layers and even in some cases with the adjacent halfinteger wind ratios. Even relatively minute speed variability withfeedback control to the drive motor causes variability in the spacingfor half and quarter integer wind ratios. Therefore, integer and halfinteger wind ratios are preferred at the outer layers of the packagewhere higher overall density can be accomplished efficiently.

Helix angle can be determined with the following equation:

$\begin{matrix}{{\tan \mspace{11mu} \theta} = \frac{V_{h}}{V_{v}}} & (2)\end{matrix}$

where V_(h) is the horizontal yarn speed and V_(v) is the vertical yarnspeed. V_(h) can be determined with the following equation:

V _(h)=2Td _(s)  (3)

where T is the traverse speed in cycles per minute and d_(s) is thetraverse stroke, which is the distance swept by the traverse guide as itmoves from one side of the package to the other. V_(v) can be determinedwith the following equation:

V _(v) =πSd _(p)  (4)

where S is the spindle speed in rpm and d_(p) is the package diameter.Yarn velocity can be calculated using V_(h) and V_(v) as follows:

V _(y)=√{square root over ((V _(h) ² +V _(v) ²))}  (5)

In most cases, V_(y) is fixed, since it is desired to maintain aconstant tension in the yarn.

Helix Angle Profile

The disclosed method can use a helix angle profile that starts at ahelix angle of about 9 degrees at the beginning of the package, peaks atabout 15 degrees towards the middle of the package, and drops to about11 degrees at the surface of the completely wound package. This helixangle profile results in a 2-20% density improvement, including about a7-17% and about a 7%-11% increase, over random winding methods whilemaintaining sufficient package uniformity and stability. In order toprevent excessive “pull-back” at reversals due to high traverse speed atthe beginning of the package, the initial helix angle must start low andthen work its way higher as the spindle speed decreases, which occurs ata relatively rapid rate of change at the beginning of a BCF package. Asthe spindle speed reduction rate levels off, the helix angle can also beleveled off, and can actually be allowed to peak and then decreasewithout causing significant package formation issues. Towards the end,or surface, of the BCF package, the helix angle is preferably allowed toramp down from its peak value in order to maintain a constant windingratio and maximize package density.

Wind Ratio at Specific Diameters of Package

Wind ratios adjacent to integer and sub-integer ribbons are avoidedthrough a substantial fraction of the package. The core of a BCF packageshould be allowed to build with wider spacing between the threadlines,and that wind ratios adjacent to integer and sub-integer ribbons shouldbe avoided within this core in order to achieve a successful packageformation (i.e. non-adjacent wind ratios). Then, only after achieving apackage diameter from about 130 mm to about 180 mm, including from about150 mm to about 180 mm, and from about 160 mm to about 180 mm, windratios adjacent to integral and non-integral ribbons can be used withoutadversely affecting the quality of BCF package formation. (i.e. adjacentwind ratios). Alternatively, random winding can be employed instead ofalternative precision non-adjacent wind methods within the firstapproximately 130 mm to about 180 mm, including from about 150 mm toabout 180 mm, and from about 160 mm to about 180 mm, of packageformation without significantly compromising package quality and overallpackage density.

After the package diameter has reached about 130 mm to about 180 mm,including from about 150 mm to about 180 mm, and from about 160 mm toabout 180 mm, it then becomes possible to choose adjacent integral andnon-integral wind ratios as part of the yarn lay down pattern on theyarn package. When choosing the appropriate integer adjacent wind ratio,the actual wind ratio chosen using the afore mentioned spacing equationshould always be less than the integer ribbon. This winding ratiopattern results in a 2-20% density improvement, including about a 7-17%and about a 7%-11% increase, over random winding methods whilemaintaining sufficient package uniformity and stability.

Wind ratio can be calculated using the following equation:

$\begin{matrix}{W = \frac{S}{T}} & (6)\end{matrix}$

where S and T are spindle speed and traverse speed described above.

Traverse Cam Control at Doffing

While not intended to be limiting, as various alternative means may becontemplated to accomplish the control strategy of the disclosed methodwith different traverse drives, the following approach enables effectivetraverse control of induction motor driven traverse cams.

FIG. 3 discloses a winding control strategy that can be used in thewinding of BCF yarns according to the disclosed method. Spindle RPMmeasurement input 2 and desired wind ratio input 4 are connected toprocessor 12 via control signals 135 and 130, respectively. Processor 12computes a traverse speed signal 115 using equation 7, which is sent toprocessor 16 and processor 14, via signal 120. Processor 14 alsoreceives traverse cam CPM measurement input 6 via control signal 140.Processor 14 sends the combined signal 110 to integral component 18. Thesoftware components of the functional blocks in FIG. 3 are programmed tointeract rapidly and precisely using components and methods known in theart, such as a programmable logic controller (PCL) or dynamic randomaccess memory. While various alternative modern computational equipmenttypes or arrangements may be contemplated, it is the logic of thestrategy that enables effective control of both winder and traverse forprecision winding of BCF yarn according to the disclosed method.

Where the traverse cam is driven by an induction motor supplied from avariable frequency drive, there is an inherent limitation in the rate atwhich the driven load speed can be changed. Due to the unique helixangle profile for the precision winding method disclosed here, anespecially rapid change in traverse cam speed is commanded at doffing,which may exceed the rate of change limitation for the induction drive.Without the following improvement, the drive would tend to trip due tothe rapid change in commanded speed, causing the winder to shut down.

The speed change limitation problem described above may be avoided byintroduction of a separate input 10 and signal 100 internal to the PLCat the moment that the winder starts the doffing sequence that causesthe output to the traverse cam drive to be filtered. This filtering,rate limiter 20, constrains the rate of change of the drive commandsignal 145 such that the inherent physical limits of the drive are notexceeded while the package is doffed and a new package is initiated.Rate limiting causes the outer layer of the package to have a randompattern that improves handling due to decrease risk of sloughing.

Traverse Speed Control

Precision winding requires precise and repeatable control of traversecam speed so that the actual winding ratio does not deviatesignificantly from the desired ratio. The method disclosed herein uses aunique speed control strategy, which enables the extremely precisecontrol of the traverse cam speed which is required for buildingefficiently laid BCF yarn packages with the desired package form.

Referring to FIG. 3, the speed of the traverse cam is monitored 6 and anactual speed signal 140 is calculated and inputed to the programmablecontroller. The controller then implements a combined feed forward andfeedback speed control loop as shown in FIG. 3. The feedback componenthas integral-only action, integral component 18, with a low gain signal125. The low gain signal 125, serves to slowly adjust the output to thetraverse cam drive, which is combined with the target traverse speedsignal 115 at component 16 to form combined signal 140, such that theerror between commanded and actual speed is driven to near zero. Lowgain improves noise immunity and reduces the variability of theresulting wind ratio. The feed forward component calculates the speedcommand 22 that would result in the correct traverse cam speed in theabsence of motor slip.

The integral component 18 can be in running state (integrates its inputvalue) or holding state (output of integrator is constant). The integral18 is put into holding state when the wind profile causes a jump incommanded wind ratio, detected by wind jump detection 8 and sent tointegral component 18 via signal 105. This ensures the integralcomponent 18 responds only to motor slip at steady state.

The command speed of the traverse cam 22 is calculated directly bymeasurement of the spindle speed (rpm) and dividing this spindle speedvalue by the desired wind ratio using the following equation:

$\begin{matrix}{T_{t} = \frac{S}{W_{t}}} & (7)\end{matrix}$

where W_(t) is the desired wind ratio and T_(t) is the desired traversecam speed.

Tension Loss Compensation

Spindle speed is typically controlled to maintain constant packagesurface speed or yarn speed (V_(y)). Because of the unique windingprofile of the disclosed method, yarn tension can be lost as helix angledecreases. Similarly, yarn tension can increase as the helix angle atthe various set points increases. To compensate for this change intension and maintain a constant yarn speed, spindle speed must be variedthroughout the winding process.

The below equation shows the relationship between spindle speed, yarnspeed, desired winding ratio, package diameter, and traverse stroke usedin the disclosed method to maintain constant tension.

$\begin{matrix}{S = \sqrt{\frac{V_{y}^{2}}{\left( {\left( \frac{2d_{s}}{W_{t}} \right)^{2} + \left( {\pi \; d_{p}} \right)^{2}} \right)}}} & (8)\end{matrix}$

Equations 2-8 can be utilized in the control strategy in FIG. 3, wherethe spindle speed is controlled to partially compensate for tensionvariation using a two component strategy. One component adjusts spindlespeed to maintain the surface speed of the package at a constant valuethroughout the package build with the value being selected according toyarn type. The second component calculates an adjustment to the targetsurface speed to partially counteract the tension variation caused bychanges in helix angle. The adjustment is rate limited to avoid controlloop instability and to avoid integral wind ratios at the jump or setpoints in the profile.

Backwinding Method

Backwinding is a process by which a full tube of yarn can be spun underspecified conditions onto another empty tube. The conditions by whichthis process should be run are listed in the table below.

Helix Angle 14.5 degrees Control Limit = +/−0.5 degrees SegregationLimit = N.A. Winding Speed- 11,680 rpm (1400 ypm) Drive Roll ControlLimit = +/−100 rpm Segregation Limit = N.A. Chuck Pressure Setting = 32Pounds Control Limit = +/−2 Pounds Segregation Limit = N.A. CleanerGuide Clearance .040 Inches (All Products) DENIER Winding Tension650-850 Aim = 180 Grams Control Limit = +/−50 DENIER Winding Tension 995-1250 Aim = 250 Grams Control Limit = +/−50 DENIER Winding Tension1260-1500 Aim = 300 Grams − Control Limit = +/−50 DENIER Winding Tension1510-1850 Aim = 350 Grams − Control Limit = +/−50 DENIER Winding Tension1860+ Aim = 400 Grams − Control Limit = +/−50

These conditions are necessary for achieving repeatable results acrossan array of products. The backwound tube must be run to a minimum of 10inches in diameter in order for package density to be valid.

EXAMPLES

The following are examples of Nylon 6,6 BCF yarn packages woundaccording to various methods, including random winding and aspects ofthe disclosed method using a Toray NXA/B wind-up. It should beunderstood that a common feature of nylon BCF and other “bulky” yarns istheir tendency to resilient recovery or “pull-back” from the edge of thepackage, and their tendency to lag behind the traverse guide as a resultof air friction. Selection of alternative yarns and polymers havingdifferent bulk and recovery features will necessitate minor adjustmentsto the profiles described.

Test Methods

Packing density is measured by dividing the weight of a wound package ofbulked continuous yarn (in grams) by the volume of yarn (in cm³). In allcases, standard tube cores were used with a fixed weight.

Dynafil™ Crimp Force (“Crimp Force”) is measured according to the testmethod in Morschel, U; Paschen, A.; Stein, W.: BCF yarn testing withDynafil ME, Chemical Fibers International, 53, pp. 204-206 (2003)(herein incorporated by reference). When the BCF nylon yarn is tested ona Dynafil™ instrument depending on the yarn speed, amount of yarnoverfeed at the top roll and the heater temperature, there is a forcedeveloped on the Tensiometer due to resistance to shrinkage. At yarnspeeds below approximately 100 mpm (meters per minute), the force isprimarly due to the shrinkage of the yarn referred to as Shrinkage Force(1). At higher speeds of over 120 mpm, the maximum yarn temperatureattained is relatively lower and a lower force is developed, referred toas Crimp Force. The measurements reported below were done on theDynafil™ at 150 mpm yarn speed under a pretension of 0.1 gpd, heatertemperature of 207° C. and 3% overfeed from the top roll.

Table 1, below, lists the various yarns wound according to the randommethod and different aspects of the disclosed method:

Sample INVISTA Crimp Force # Product # Cross-Section Denier at 150 mpm.1 966-80-826 Modified 966 7.50 Trilobal 2 995-80-476 Mickey with 9955.35 Three lobes 3 1045-80-276AS Mickey with 1045 5.80 Three lobes 41120-61-736AS Modified 1120 11.37 trilobal 5 1130-68-746 Trilobal 11309.38 6 1185-68-846 Trilobal 1185 9.61 7 1205-68-746 Modified 1205 10.94Trilobal 8 1340-68-416 Trilobal 1340 11.33 9 1491-68-246 Trilobal 149114.42 10 1045-80-276AS Mickey with 1045 5.80 Three lobes

Example 1

Example 1 compares the package density (grams per cm³) of yarn Samples 1to 9 wound using a random winding method and the precision windingmethod described above in FIG. 1.

Sample Density-Random Density-FIG. 1 Packing Density # (g/cm³) (g/cm³)Increase (%) 1 0.46 0.511 11.1 2 0.57 0.6115 7.3 3 0.53 0.575 8.5 4 0.370.43 16.2 5 0.503 0.55 9.3 6 0.4915 0.54 9.9 7 0.38 0.44 15.8 8 0.420.49 16.7 9 0.41 0.45 9.8

Example 2

Example 2 compares the packing density (grams per cm³) of yarn Sample 10wound using a random winding method and the precision winding methoddescribed above in FIG. 2.

Sample Density-Random Density-FIG. 2 Packing Density # (g/cm³) (g/cm³)Increase (%) 10 0.4904 0.5036 2

The invention has been described above with reference to the variousaspects of the disclosed method and products. Obvious modifications andalterations will occur to others upon reading and understanding theproceeding detailed description. It is intended that the invention beconstrued as including all such modifications and alterations insofar asthey come within the scope of the claims.

1-12. (canceled)
 13. A package of bulked continuous filament yarn havinga final diameter comprising a packing density of from about 0.4 gramsper cm³ to about 0.6 grams per cm³, wherein said package furthercomprises a non-adjacent winding pattern ending at a package diameterfrom about 47% to about 65% of said final diameter, and a precisionadjacent winding pattern starting at a package diameter of from about47% to about 65% of said final diameter.
 14. The package of bulkedcontinuous filament yarn of claim 13, wherein said non-adjacent windingpattern comprises random winding.\
 15. The package of bulked continuousfilament yarn of claim 13, wherein said packing density is from about0.5 grams per cm³ to about 0.55 grams per cm³.
 16. The package of bulkedcontinuous filament yarn of claim 13, further comprising a packingdensity increase of from about 7% to about 17% over a randomly woundpackage of said yarn.
 17. The package of bulked continuous filament yarnof claim 13, wherein said yarn is Nylon 6,6. 18-22. (canceled)
 23. Apackage of bulked continuous filament yarn wound according to the methodof claim 13, said package comprising a packing density increase of fromabout 7% to about 17% over a randomly wound package of said yarn. 24-27.(canceled)
 28. A package of bulked continuous filament yarn having afinal diameter comprising a packing density of from about 0.4 grams percm³ to about 0.6 grams per cm³, wherein said package further comprises anon-adjacent winding pattern ending at a package diameter to tube corediameter ratio from about 1.6:1 to about 2.3:1, and a precision adjacentwinding pattern starting at a package diameter to tube core diameterratio from about 1.6:1 to about 2.3:1.
 29. (canceled)
 30. A package ofbulked continuous filament yarn having a ratio of packing density(measured in grams per cm³) to final package diameter (measured in cm)greater than 0.018:1.
 31. The package of bulked continuous filament yarnof claim 30, wherein said ratio is between 0.018:1 to about 0.022:1. 32.The package of bulked continuous filament yarn of claim 30, wherein saidratio is between 0.019:1 to about 0.022:1.
 33. The package of bulkedcontinuous filament yarn of claim 30, wherein said ratio is between0.020:1 to about 0.022:1.
 34. The package of bulked continuous filamentyarn of claim 30, wherein said ratio is between 0.021:1 to about0.022:1. 35-36. (canceled)